The British troops made little headway, advancing only one kilometre (less than a mile) from the south in the direction of the city centre, according to an AFP correspondent on the outskirts.

Iraqi forces aimed rocket-propelled grenades and machine-gun fire at British positions and an Iraqi T-55 tank was seen advancing towards the frontline, according to a journalist embedded with the British troops.

But British troops, known as Desert Rats, destroyed the tank and a bunker, and captured 12 Iraqi prisoners of war as they established what they called an advanced vehicle checkpoint.

Lieutenant Colonel David Paterson said the aim of the checkpoint was to "poke a toe into Basra to see what happens."

"The purpose is to get information from the civilians going in and out of the city about what is happening right inside," he added.

"We need to establish that interface because we need to know the conditions there before we go into Basra."

The British forces' chief spokesman Colonel Chris Vernon said that "there are somewhere around a thousand" irregular Iraqi troops within the city.

"It's quite clear that elements of (the Iraqi army's) 51 brigade that we gave an opportunity to capitulate have pulled back inside," he added.

The spokesman said that it was impossible to put a figure on the number of regular troops still inside the city, as many were changing in and out of uniform.

But he said that many were being forced to fight by the militia and had abandoned much of their equipment on the outskirts of the city.

Vernon said the British had no immediate plans to launch an all-out assault on the city but they were able to stage incursions on a regular basis.

"We are in and out as we see fit. We will go in, come out, and one day we will stay."

Britain's Defence Secretary Geoff Hoon said the campaign to take control of Basra was well on course.

"Key suburbs of Basra have been taken. We can move further into the city," Hoon told parliament in London Thursday.

But Iraqi Information Minister Mohammad Said al-Sahhaf rejected any suggestion that Basra was on the verge of being captured.

"Basra is still there. She is strong. All the Iraqi units are there," he told a press conference in Baghdad.

Vernon denied that British troops were besieging Basra, saying that a passage in the northeast had been left "entirely open" for residents to come and go.

He also said that residents inside the city had provided intelligence on members of the ruling Baath party. "They are telling us where the Baath party is meeting and within hours that meeting place will no longer exist."

Some 3,500 Iraqi prisoners of war were being held at a British detention centre around the southern port of Umm Qasr, including several senior military and Baath party officials who were also "giving some pretty good intelligence", Vernon said.

The coalition had hoped that the Shiite Muslim residents of Basra would rise up in an echo of a revolt after the end of the last Gulf War 1991 which was brutally crushed by Saddam.

But Vernon said locals had not forgotten how they were left to meet their fate in 1991 and were still reluctant to believe Saddam's days were numbered.

"The legacy created by that is making it very, very difficult to achieve what we are trying to do."

British soldiers manning checkpoints into Basra began giving out leaflets to Iraqis on Thursday.

"This time we won't abandon you. Be patient, together we will win," read the leaflet, which showed a British soldier shaking hands with an Iraqi man.

SPACE.WIRE